JPH0364577B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a method for manufacturing a whisker-reinforced metal composite material having excellent strength properties, in which SiC whiskers and Al powder particles are homogeneously mixed. "Conventional technology" Because whiskers have excellent specific strength, specific modulus, and heat resistance, whisker-reinforced metal composites made by dispersing them in metals such as Al, Mg, Ti, and Cu or their alloys have been developed. It is considered useful in various application fields that require weight reduction and improved strength properties. The performance of this metal composite material is largely influenced by the dispersibility of whiskers in the matrix metal, and it is important to homogeneously disperse fine fibers such as whiskers in the matrix metal to improve strength properties. . Another important factor is that the whiskers dispersed in the matrix metal remain in the composite material while maintaining their shape characteristics without being broken or destroyed. Usually, a whisker product exhibits an aggregated structure in which fine short fiber-like single crystals are intertwined in no direction. Therefore, it is difficult to homogeneously disperse this whisker product directly into the molten metal that will become the matrix by means such as stirring and mixing. As a solution to this problem, a method has been proposed in which a metal composite is manufactured by a powder metallurgy method in which whiskers and matrix metal powder are mixed and the mixture is hot-pressed. "Problems to be Solved by the Invention" In this case, in order to impart high strength properties to a metal composite material, it is necessary to ensure the homogeneity of the mixture of whiskers and metal powder particles and the damage to the whiskers during the mixing and hot pressing process. It is necessary that there is little deformation. In other words, in a mixture of whiskers and metal powder, columnar whiskers exist in the grain boundary voids of the metal powder particles, so the homogeneity of the mixture depends on the interaction between the sizes of the columnar whiskers and the metal powder particles. is an important element. Further, during the mixing and hot-pressing process, the whiskers are easily damaged and deformed due to collision and contact with metal powder particles. Therefore, it is necessary to improve the properties of the mixed powder and prevent damage and deformation of the whiskers in order to produce metal composites with excellent strength properties. The influence of shape and size is important. "Means for Solving the Problems" From these viewpoints, the present invention provides a method for manufacturing metal composite materials with high strength properties by regulating the shapes and sizes of the whiskers and metal powder particles used within specific ranges. This is a proposal. That is, the present invention provides a method for producing a metal composite material in which whiskers and metal powder particles are mixed and then hot-pressed. The method for producing a whisker-reinforced metal composite material is characterized in that Al powder particles having a particle size of 15 μm or less are stirred and mixed, then overdried, and the resulting mixture is hot-pressed. In the present invention, SiC as reinforcing whisker
SiC whiskers consisting of acicular single crystals are used, and Al powder particles are used as the metal matrix. The method for preparing the mixture of whiskers and metal powder particles is the method previously proposed by the applicant (Japanese Patent Application No. 1983-
173548) is preferably applied. That is,
As a dispersion medium for stirring and mixing whiskers and metal powder particles, an organic solvent such as alcohol, acetone, or ether is used. As the stirring mixer, it is preferable to use a jet-type stirrer, a high-speed rotation stirrer, or the like to perform relatively strong stirring and mixing.
In this case, the dispersion concentration should be adjusted to completely loosen the whisker aggregates and disperse them uniformly.
It is set to 60g/or less. After this whisker dispersion is filtered with stirring to remove a portion of the dispersion medium, metal powder particles are immediately added to prepare a dispersion in which SiC whiskers and Al powder particles are uniformly mixed. At this time, a predetermined amount of metal powder particles is added based on the setting of the composite ratio of matrix metal and whiskers in the composite material. In addition, the concentration of the mixture of whiskers and metal powder particles, which are dispersoids, is adjusted to a range of 350 to 1100 g/l in order to maintain a uniform mixed and dispersed state. This dispersion is rapidly filtered while stirring to maintain a uniform dispersion state, and the resulting cake is dried, and then this mixed powder is hot-pressed to produce a whisker-reinforced metal composite material. In the present invention, by regulating the shape and size of the whiskers and metal powder particles to be used within a specific range, the metal composite has a homogeneous structure and has excellent strength characteristics with less damage to the shape characteristics of the whiskers. This makes it possible to manufacture materials. In order to homogenize the structure of metal composites,
It is necessary that the whisker and metal powder particles be relatively small and similar in size. Furthermore, in order to exhibit the reinforcing effect of the whiskers, it is also important to have an appropriate aspect ratio. On the other hand, long whiskers are easily damaged by collision or contact with metal powder particles. In addition, the presence of large metal powder particles inhibits uniform plastic flow during hot-press molding, which tends to cause structural defects in the metal composite and causes significant damage to whiskers. The present invention investigates the relationship between the sizes of whiskers and metal powder particles by adjusting the diameter of SiC whiskers to 0.1 to 0.2μ.
m, length 15μm or less, aspect ratio 50 or more,
Furthermore, by regulating the particle size of the Al powder particles to 15 μm or less, it becomes possible to produce a metal composite material that is highly homogeneous and has excellent strength characteristics with little damage to the shape of whiskers. "Operation" As explained above, in the present invention, by making the sizes of SiC whiskers and Al powder particles relatively small and similar, the whiskers can be easily distributed evenly in the grain boundary voids of metal powder particles. . Furthermore, damage to the whiskers is effectively reduced during the hot-press molding process, and deterioration of the composite reinforcing function of the whiskers is prevented. "Example" SiC whiskers with different shape characteristics were prepared, mixed with pure Al powder particles with different particle sizes by stirring and dispersing in ethyl alcohol, and then overdried to obtain a mixed powder. This mixed powder was photographed by SEM (50x and 500x magnification), and the state of the structure was observed. Next, this mixed powder was heated at a temperature of 640℃ and a pressure of 1500Kg/ ^cm2.
A whisker-reinforced metal composite material with a diameter of 50 mm and a height of 100 mm was prepared by heat-pressure treatment for 60 minutes, and its structure was observed using SEM photographs (100x and 1000x magnification).
Their homogeneity was compared. These results are summarized in Table 1.

[Table] Next, the mechanical strength characteristics of this whisker-reinforced metal composite material are compared and shown in Table 2.

[Table] "Effects of the Invention" As is clear from the above explanation, according to the present invention,
It is possible to obtain a homogeneous mixed powder of SiC whiskers and Al powder particles, and even in the composite material, whisker-reinforced metal composite materials have excellent strength properties and are easy to extrude because they are homogeneous and have little damage to the shape of the whiskers. It becomes possible to manufacture.

Claims (1)

[Claims] 1. A method for producing a metal composite material in which whiskers and metal powder particles are mixed and hot-press molded, in which SiC whiskers with a diameter of 0.1 to 0.2 μm, a length of 15 μm or less, and an aspect ratio of 50 or more and a particle size of 15 μm are mixed in an organic solvent.
1. A method for producing a whisker-reinforced metal composite material, which comprises stirring and mixing Al powder particles having a size of less than m, followed by filtering and drying, and hot-pressing the resulting mixture.